This invention relates to a lens system having a stripe filter between the last lens surface and the focal plane, and more particularly to zoom lenses.
Excellent quality lens systems and particularly the zoom lenses for color television cameras must have excellent imaging characteristics and color reproductivity.
In case where as the color separation, use is made of a three-color separation prism between the last surface of the lens system and the focal plane. The difference of the angle of incidence of the light rays on the individual parts of the dielectric multi-layer coating provided for color separation breaks the uniformity of spectral characteristics and polarizing characteristics, causing color deviation between the central and marginal zones of the image pick-up surface. A proposal for the solution of this is given in Japanese Patent Sho 53-42370 or U.S. patent application Ser. No. 175,523, now U.S. Pat. No. 4,444,472.
In the two-tube or single tube type of system, where a stripe filter is used as the color separation system, the gap between the stripe filter and the image pick-up plane causes the phase in the image pick-up plane to differ with the distance from the center of the picture area to the margin thereof, which in turn causes color deviation. However, the use of the stripe filter is accepted in the type of lenses where the distance between the last lens surface and the focal plane is short as compared with the use of the color separation prism. Therefore, mere application of the conventional means does not suffice.